See the sketch on my GitHub page here.
The At24C246 EEPROM can be used to add a few bytes of permanent memory to an Arduino project. Although there are a total of 256 bytes available, this is arranged in pages of 32 bytes you cannot save a character across a page boundary. There is an excellent description and instructions for use on the Hobbytronics website here.
This memory can be used to store setting for a clock etc, that can be loaded into the Arduino as it powers up